text: Hemichromes can be classified in two main categories: reversible and irreversible.
  Reversible hemichromes (Hch-1) have the ability to return to their native formation (hemoglobin). Some hemichromes can be reduced to the high-spin state of deoxyhemoglobin, while others are first being reduced to hemochromes (FeII) and then to deoxyhemoglobin through anaerobic dialysis. Photolysis, in the presence of oxygen from CO and its reaction with the hemochrome, can quickly convert a hemichrome to oxyhemoglobin (HbO2).
  Irreversible hemichromes (Hch-2) cannot be converted to their native form.
  Both the reversible and irreversible hemichromes have a similar rate during proteolytic degradation and they both have a lower percentage of alpha helixes.